Barlow's law applications
Barlow's law applications
(OP)
i am new to barlow's law,
we are trying to determine the min wall thickness of HDPE bottle utilizing Barlow's law we would like to hear your comments on such approach is it valid to use such equation to our purpose also we would like to know what does design stress mean in barlow's law and how can we calculate it or obtain it
thanks a lot
we are trying to determine the min wall thickness of HDPE bottle utilizing Barlow's law we would like to hear your comments on such approach is it valid to use such equation to our purpose also we would like to know what does design stress mean in barlow's law and how can we calculate it or obtain it
thanks a lot





RE: Barlow's law applications
RE: Barlow's law applications
but do you have any info concerning the design stress
thanks a lot
RE: Barlow's law applications
RE: Barlow's law applications
Your key consideration is how long do you want the item to last / be under pressure or stress of any sort and what temperature are you going to operate it at.
Then use the graphs and data from the stress graphs listed in the document.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Barlow's law applications
RE: Barlow's law applications
http://en.wikipedia.org/wiki/Barlow's_law
the first sentence of that link is "Barlow's law was an incorrect physical law proposed by Peter Barlow in 1825 to describe the ability of wires to conduct electricity."
Can you elaborate for us on what "Barlow's law" means to you?
RE: Barlow's law applications
the one that am asking for is in the following link
http://en.wikipedia.org/wiki/Barlow's_formula
this formula tries to relate the internal pressure with the wall thickness of pipes
RE: Barlow's law applications
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Barlow's law applications
filling bottles with tablets ... how does that produce an internal pressure ?
or are you tlaking about the bottle moulding process ?
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RE: Barlow's law applications
RE: Barlow's law applications
I suspect the approach here would result in the same thing, a bottle which would hold the tablets etc ok, but then buckle and collapse as soon as you tried to hold it and remove the child
proofresistant cap on the top of it....My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Barlow's law applications
a) No
b) From a material data sheet from the supplier.
As alluded to above, you probably have stiffness issues more than strength ones. Mr Barlow's Law (thanks for that, interesting that it was derived so long ago) only talks about stresses as a result of uniform internal or external pressure.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Barlow's law applications
the orgin location is 1000m over sea level while NJ is at sea level so there is pressure deffirance betweent he two locations
we are trying to find a preventive action to prevent this phonomenon from occuring again in other products and thats what led us to barlow's law to find the optimal thickness that can prevent the bottles from paneling
RE: Barlow's law applications
What you are describing sounds like local skin buckling of a thin walled pressure vessel, the great news is that it is well understood, the bad news is that it is a bit more complex than Pd/2t.
http://www.eng-tips.com/viewthread.cfm?qid=91966
The net result is the same, reduce the pressure or increase the wall thickness.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Barlow's law applications
Odd for this to be the critical design load ... i'd've thought the the crusshing load from someone opening the container would be more. the problem if that i think FE will not predict buckling of the container under external pressure.
I think you may need to do some tests, with a vaccuum machine, develop a 2psi vaccuum inside the container.
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RE: Barlow's law applications
RE: Barlow's law applications
RE: Barlow's law applications
we have tryed to simulate the sea conditions by placing the bottles in a pressurized vessel paneling has occured hoewever when the size of the bottle was reduced no paneling was observed (from 625 to 500 cc) we are trying to find a preventive action to stop this from happening to other bottles.
RE: Barlow's law applications
if you get good results for the smaller bottle, then you know an acceptable stress (pR/t).
so the 625cc bottles should have a wall thickness 1.25* the 500cc bottles, yes?
haven't we made pill containers for a long time ? don't we know from experience what work and what doesn't ?
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RE: Barlow's law applications
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Barlow's law applications
Quando Omni Flunkus Moritati
RE: Barlow's law applications
if you know what plane i'm talking about, i know too (intentionally not mentioning it).
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